World No. 1 Serena Williams has officially withdrawn from both Indian Wells and Miami citing a left knee injury.

“Sadly, I have to withdraw from the BNP Paribas Open in Indian Wells and the Miami Open,” Williams said in a statement. “I have not been able to train due to my knees and am disappointed I cannot be there. I will keep moving forward and continue to be positive. I look forward to being back as soon as I can.”

She had also won the Miami title eight times. And her withdrawals will likely result in her loss of the No. 1 ranking to Angelique Kerber who can have it back by reaching the Indian Wells quarterfinals.